Systems for retarding the speed of a railcar

ABSTRACT

A system for retarding the speed of a railcar comprises a brake; a hydraulic actuator moving the brake between a closed position in which the brake applies braking pressure on the wheel of a railcar, and an open position in which the brake does not apply braking pressure on the wheel of the railcar; a hydraulic circuit provided with a pump arrangement for supplying hydraulic fluid to the hydraulic actuator; and a control circuit coupled to the hydraulic circuit for controlling the flow of hydraulic fluid to move the brake between the closed and open positions.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 14/555,088, filed Nov. 26, 2014. The '088 application claimspriority to and the benefit of U.S. Provisional Patent Application Ser.No. 61/951,151 filed Mar. 11, 2014 which are both incorporated herein inentirety.

FIELD

The present disclosure relates generally to retarders of the kindsuitable for reducing the speed of a railcar riding along a set ofrails.

BACKGROUND

U.S. Pat. No. 4,393,960, the disclosure of which is hereby incorporatedherein by reference in entirety, discloses a brake shoe structure thatincludes a series of alternating long brake shoes and short brake shoesmountable on adjacent brake beams in a railroad car retarder. The lengthof the long brake shoe is such that the long brake shoe symmetricallystraddles two adjacent brake beams. The length of the short brake shoeis such that the shoe occupies the spacing on the brake beams betweentwo long brake shoes. The long brake shoes are affixable to each of thebrake beams in at least two locations. The brake shoes contain aplurality of slanting slots in their braking surfaces for interruptingharmonics producing screeching noises during retardation. The brakeshoes may be formed of steel or heat treatable ductile iron.

U.S. Pat. No. 7,140,698, the disclosure of which is hereby incorporatedherein by reference in entirety, discloses a hydraulic control andoperating system for a railroad car retarder to control the movement ofrailroad cars in a railroad classification yard. The system utilizes adouble-acting hydraulic cylinder to operate the retarder mechanism andincludes a hydraulic control circuit that provides protection againstpressure spikes and high pressure excursions, high and low temperatureexcursions, low oil levels and oil filter fouling. The system shutsitself down to prevent damage, and provides a warning to maintenancestaff that service should be performed long before a need for systemshut-down is required. The system includes a central operating panel inthe rail yard control center, a remote control panel located at theposition of the retarder, and the system can be connected for operationfrom a completely remote location.

U.S. Pat. No. 8,413,770, the disclosure of which is hereby incorporatedherein by reference in entirety, discloses systems for and methods ofoperating electro-hydraulic retarders. In one example, a system isprovided for retarding the speed of a railcar. The system includes abrake, a hydraulic actuator coupled to the brake, and a hydrauliccircuit that directs pressurized hydraulic fluid to the actuator. Thefluid causes the actuator to move the brake towards a closed position inwhich the brake will apply a predetermined braking pressure on a wheelof the railcar. A hydraulic accumulator is coupled to the hydrauliccircuit and configured to accumulate fluid from the hydraulic circuitwhen the wheel forces the brake out of the closed position and to supplypressurized accumulated fluid back to the hydraulic circuit when thebrake moves back into the closed position to thereby maintain asubstantially constant braking pressure on the wheel of the railcar asit moves through the brake.

U.S. Pat. No. 8,499,900, the disclosure of which is hereby incorporatedherein by reference in entirety, discloses electro-hydraulic retardersdesigned to allow opposing brake shoes on the retarder to spread to thewidth of a wheel entering the retarder, and yet still maintain a desiredbraking pressure on the sides of the wheel. In one example, the retarderincludes a brake and a brake actuator that has a piston-cylinder and aspring. One or both of the piston and the cylinder acts on the brake andthe other of the piston and the cylinder acts on one end of the spring.The other end of the spring acts on the brake. In one example, thespring is wrapped around the cylinder and connected thereto in series.In such an arrangement, supplying pressurized hydraulic fluid to thepiston-cylinder causes both the piston-cylinder and the spring to movethe brake towards a closed position in which the brake will apply apredetermined braking pressure on a wheel of the railcar. The springresiliently biases the brake into the closed position to maintain asubstantially constant braking pressure on the wheel of the railcar asit moves through the retarder.

U.S. Patent Application Publication No. 2011/0315491, the disclosure ofwhich is hereby incorporated herein by reference in entirety, disclosessystems for retarding the speed of a railcar. In one example, ahydraulic actuator moves a brake between a closed position in which thebrake applies braking pressure on a railcar wheel, and an open positionin which the brake does not apply braking pressure on the railcar wheel.A pump supplies hydraulic fluid into at least one of a first manifoldand a second manifold of a hydraulic circuit. A logic element reacts tomaintaining a selected pressure in the first manifold when a railcarwheel enters a brake and moves the brake from the closed position to theopen position to cause a selected braking pressure to be applied to therailcar wheel. A control circuit controls the logic element to apply theselected braking pressure on the railcar wheel.

SUMMARY

The present disclosure arises from the present inventors' research anddevelopment of electro-hydraulic systems for retarding the speed of arailcar traveling on a set of rails. The inventors have recognized thatmore efficient and effective electro-hydraulic retarder systems andmethods of operating such systems are needed in the art. For example, incurrent electro-hydraulic retarder systems, when a wheel enters thesystem, the system is ideally capable of allowing the brake shoes tospread apart to the width of the wheel and yet still maintain a desiredpressure on the side of the wheel. The system ideally also allows forquick application and removal of pressure on the sides of the wheel.However, the present inventors have realized that because hydraulicfluids are generally incompressible, it is difficult to use hydraulicsto power the system in such a way that the brake shoes will quicklyspread apart to accept an entering wheel and conform to various widthsof railcar wheels while maintaining consistent pressure on the sides ofthe wheel. Through research and development, the inventors have inventedthe systems and methods disclosed herein, which overcome many of thesedeficiencies in the prior art.

In one example, a system for retarding the speed of a railcar comprisesa brake; a hydraulic actuator moving the brake between a closed positionin which the brake applies braking pressure on a wheel of the railcar,and an open position in which the brake does not apply braking pressureon the wheel of the railcar; a hydraulic circuit configured with a firstmanifold and a second manifold, and provided with a pump arrangement forsupplying hydraulic fluid to the hydraulic actuator; and a controlcircuit coupled to the hydraulic circuit for controlling the flow ofhydraulic fluid to move the brake between the closed position and theopen position, wherein the pump arrangement includes a first pump and asecond pump, the first pump being used in providing powered movement ofthe brake to the closed position and at least the second pump being usedin providing powered movement of the brake to the open position, andwherein the control circuit and the hydraulic circuit are configured toprovide a non-powered movement of the brake to the open position.

In another example, a hydraulic accumulator is connected to the pumparrangement, wherein the pump arrangement is periodically energized tocharge the accumulator so that, upon a de-energization of the pumparrangement, the hydraulic accumulator provides pressurized hydraulicfluid which is used to provide movement of the brake to the closedposition.

In a further example, the hydraulic actuator includes a piston disposedin a cylinder, wherein pressurized hydraulic fluid enables the piston toextend from the cylinder into an extended position to move the brakeinto the closed position, and wherein pressurized hydraulic fluidenables the piston to retract into the cylinder in a retracted positionto move the brake to the open position. The piston defines an orificetherethrough in communication with a check valve, and wherein theorifice and the check valve facilitate flushing of hydraulic fluid froma rod-side of the cylinder to a cap-side of the cylinder when the pistonis moved from the extended position to the retracted position.

In an additional example, the hydraulic circuit includes a pressurecontrolling arrangement responsive to different signals from the controlcircuit for selecting and maintaining a selected system pressure of thehydraulic fluid in the hydraulic circuit, and an anti-cavitation checkvalve connected to the pressure controlling arrangement. When the wheelenters the brake and forces the brake towards the open position, thepressure controlling arrangement reacts to an increase in the pressureof the hydraulic fluid, and directs an amount of hydraulic fluid to thereservoir to avoid over-pressurization and maintain the selected systempressure, and the check valve directs a portion of the hydraulic fluiddirected to the reservoir to a rod-side of the cylinder to preventcavitation during a rapid movement of the piston rod.

Further examples are provided herein and will be described hereinafterwith reference to the following drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a pair of rails and a retarder system forreducing the speed of a railcar riding on the rails.

FIG. 2 is a side view of the pair of rails and retarder system depictedin FIG. 1.

FIG. 3 is a plan view of the pair of rails shown in FIG. 1, furtherdepicting hydraulic systems for operating the retarder system.

FIG. 4 is a sectional view taken through Section 4-4 in FIG. 1 showing abrake.

FIG. 5 is a sectional view of an actuator, including a piston,piston-rod and cylinder.

FIG. 6 is a side view of the actuator.

FIG. 7 is a schematic view of an electro-hydraulic system for operatingthe retarder system.

FIG. 8 is a schematic view of the system of FIG. 7 showing charging ofan accumulator.

FIG. 9 is a schematic view of the system of FIG. 7 showing theaccumulator being fully charged.

FIG. 10 is a schematic view of the system of FIG. 7 showing a poweredclosing of the brake and a discharging of the accumulator into a BrakingState.

FIG. 11 is a schematic view of the system of FIG. 7 when the brake isclosed and a railcar wheel enters the brake.

FIG. 12 is a schematic view of the system of FIG. 7 showing anon-powered opening of the brake into a Relaxed State.

FIG. 13 is a schematic view of the system of FIG. 7 showing a poweredopening of the brake into a Power Open/Flush State.

FIG. 14 is a schematic view of the system of FIG. 7 showing a coolingloop.

FIG. 15 is a schematic view of the system of FIG. 7 showing anaccumulator repair/replacement.

DETAILED DESCRIPTION OF THE DRAWINGS

In the present disclosure, certain terms have been used for brevity,clearness and understanding. No unnecessary limitations are to beimplied therefrom beyond the requirement of the prior art because suchterms are used for descriptive purposes only and are intended to bebroadly construed. The different systems and methods described hereinmay be used alone or in combination with other systems and methods.Various equivalents, alternatives and modifications are possible withinthe scope of the appended claims.

FIGS. 1 and 2 depict a railcar retarder system 20 that is mounted alonga section of track 22, including a pair of conventional rails 24. Thesection of track 22 continues in both directions from the system 20 withrailcars entering the system 20 from the left in the direction shown byarrow 26 and exiting to the right in the direction shown by arrow 28.The retarder system 20 includes a series of pairs of brakes 30positioned on opposite sides of each of the rails 24. The brakes 30 arepositioned alongside and on top of the rails 24 such that, whenactuated, the brakes 30 engage the sides of the railcar wheels to brakeor retard the moving railcar. Although the particular example showndepicts a two series 29 a, 29 b (see FIG. 3) of six pairs of brakes 30,it should be recognized that the number and arrangement of the brakes 30can vary from that shown depending upon various operational parameters.In the example shown, each series 29 a, 29 b includes six pairs ofbrakes 30 that are connected in series to a power unit comprising ahydraulic circuit 32. In use, each hydraulic circuit 32 receives anddirects pressurized hydraulic fluid to the brakes 30 to actuate thebrakes 30, as is further discussed herein below.

FIG. 3 is a view showing the retarder system 20 and more particularlyshowing the hydraulic circuit 32. Portions of the brakes 30 are omittedto more clearly show the hydraulic circuit 32.

FIG. 4 depicts Section 4-4 of FIG. 1. FIG. 4 is representative of eachpair of brakes 30 in the retarder system 20. Generally, each brake 30includes rail supports 34 to which a rail 24 is secured. Each railsupport 32 contains a fulcrum pin 36 supporting upper and lower levers38, 40, which together function as a brake 30. The fulcrum pin 36 passesthrough an end of upper lever 38 and also through a center portion oflower lever 40. A brake beam 48 is secured to each of the levers 38, 40.The position of the brake beam 48 on the levers 38, 40 can be adjustedby an adjustment mechanism extending through flanges on the lever arms,according to known arrangements such as those described in U.S. Pat. No.4,393,960. Brake shoes 50 are mounted on the brake beams 48. The brakeshoes 50 are generally L-shaped, having a short arm containing brakingsurface 54 supported by a flange mounted to the brake beam 48. Thehydraulic circuit 32 is connected to a hydraulic actuator, which ismovable under hydraulic forces to move the retarder between the open andclosed positions. Different types of hydraulic actuators could be used,such as for example a plunger cylinder and/or the like. In theparticular example shown, the actuator includes a hydraulicpiston-cylinder 42 having a cylinder 44 connected to the end of one ofthe levers 38, 40 and a piston-rod 46 connected to the other.

FIGS. 5 and 6 show a sectional view and side view, respectively, of anexemplary piston-cylinder 42. The piston-cylinder 42 includes a pair ofhydraulic ports including a rod-side port 58 and a cap-side port 60. Apiston 62 is disposed on the internal end of the piston-rod 46 anddivides the cylinder 44 into two chambers 64, 66, including a rod-sidechamber 64 and a cap-side chamber 66. The piston 62 is connected topiston-rod 46, which extends from the piston-cylinder 42. Rod-sidehydraulic port 58 is in fluid communication with rod-side chamber 64 andcap-side hydraulic port 60 is in fluid communication with cap-sidechamber 66. A passageway in the form of a dampening orifice 68 isdefined in the piston 62 and facilitates flow of hydraulic fluid betweenthe rod-side chamber 64 and the cap-side chamber 66. As will bedescribed hereafter, the dampening orifice 68 is used in conjunctionwith a check valve 186 in the piston cylinder 42 to further control theflow of hydraulic fluid between the chambers 64, 66, such as, forexample, one way flow only from the rod-side chamber 64 to the cap-sidechamber 66.

In use, the hydraulic circuit 32 conveys hydraulic fluid to and from thepiston-cylinders 42 and controls the pressure of the hydraulic fluid tomove the brake 30 between its closed position and its open position andto apply selected braking pressures to the wheel of the railcar.Specifically, the hydraulic piston-cylinder 42 is movable underhydraulic pressure from the circuit 32 between an extended position,wherein the piston-rod 46 extends from the cylinder 44 to move the brake30 into the closed position and a retracted position wherein thepiston-rod 46 retracts into the cylinder 44 to move the brake 30 intothe open position. When it is desired to retard the motion of a railcarriding on rails 24 a Braking State is initiated, hydraulic fluid isprovided to one end of the piston-cylinder 42 via the hydraulic circuit32 to actuate the piston-cylinder 42 to extend piston-rod 46. Thepiston-cylinder 42 pivots the ends of levers 38, 40 apart, and thusmoves the brake shoes 50 towards each other and into contact with arailcar wheel. Brake shoes 50 contact the inside and outside of arailcar wheel riding on the rail to apply a braking pressure. Todecrease braking force during the Braking State, the fluid pressure onthe end of the piston-cylinder 42 is decreased. To terminate theretarding action the fluid pressure on the end of the piston-cylinder 42is removed and the return springs 55, 57 and the weight of the upperlever 38 move the ends of levers 38, 40 together and thus move the brakeshoes 50 outwardly away from the railcar wheel and into a Relaxed State.The brake shoes 50 can also be moved outwardly away from the railcarwheel and into a Power Open/Flush State by providing hydraulic fluid toan opposite end of the piston-cylinder 42 to actuate the piston-cylinder42 to retract piston-rod 46.

A non-limiting example of the hydraulic circuit 32 and relatedcomponents will now be described with reference to drawing FIG. 7. Thehydraulic circuit 32 is configured with a first section or manifold 32 aand a second section or manifold 32 b. FIG. 7 depicts the hydrauliccircuit 32 including a first cylinder bank 100 and a second cylinderbank 102. In the example shown, each of the banks 100, 102 includes aseries of eight piston-cylinders 42 which are interconnected together inseries to selectably control opening and closing of brakes 30 associatedwith the piston-cylinders 42. It should be recognized that othercylinder bank configurations are contemplated by this disclosure.

The retarder system 20 also includes a control circuit C which can belocated adjacent to and/or remotely from the retarder system 20. Thecontrol circuit C can include one or more control circuit sections. Eachsection is generally a computing system that includes a processingsystem, storage system, software, communication interface, andoptionally a user interface. The processing system loads and executessoftware from the storage system, including a software module. Whenexecuted by the computing system, software module directs the processingsystem to operate as described herein in further detail in accordancewith the methods of the present disclosure. While a description asprovided herein refers to a computing system and a processing system, itis to be recognized that implementation of such systems can be performedusing one or more processors, which may be communicatively connected,and such implementations are considered to be within the scope of thedisclosure. The processing system can include a microprocessor and othercircuitry that retrieves and executes software from a storage system.Processing systems can be implemented with a single processing devicebut can also be distributed across multiple processing devices orsubsystems that cooperate in executing program instructions. Examples ofprocessing systems includes a general purpose central processing unit,application specific processor, logic devices, as well as other types ofprocessing devices, combinations of processing devices, or variationsthereof. Storage systems can include any storage media readable by aprocessing system and capable of storing software. The storage systemcan include volatile and non-volatile, removable and non-removable mediaimplemented in any method or technology for storage of information, suchas computer readable instructions, data structures, program modules, orother data. Storage systems can be implemented as a single storagedevice, but may also be implemented across multiple storage devices orsubsystems. Storage systems can further include additional elements,such as a controller, capable of communicating with the processingsystem. Each storage media can include random access memory, read onlymemory, magnetic disks, optical disks, flash memory disks, virtual andnon-virtual memory, magnetic sets, magnetic tape, magnetic disk storageor other magnetic storage devices, or any other media which can be usedto store the desired information and that may be accessed by aninstruction execution system, as well as any combination or variationthereof, or any other type of storage media. In some implementations,the storage media can be a non-transitory storage media. User interfacecan include a mouse, a keyboard, a voice input device, a touch inputdevice for receiving a gesture from a user, a motion input device fordetecting non-touch gestures and other motions by a user, and othercomparable input devices and associated processing elements capable ofreceiving user input from a user. Output devices such as a video displayor a graphical display can display an interface further associated withembodiments of the system and method as disclosed herein.

The control circuit C is configured to send and receive commands orsignals with a location yard monitor system M, such as by means of adetector, radar, laser and the like, to determine the position of amoving railcar in the retarder system 20. As a railcar approaches theretarder system 20, the yard monitor system M monitors environmentalfactors and/or characteristics of the railcar such as weight, velocity,direction and the like, and calculates an amount of braking pressurenecessary to achieve a desired railcar speed, all as is conventional.Based upon the calculation, the control circuit C is programmed, such asby a programmable logic controller (PLC), to control operations of thevarious components of the retarder system 20 via one or more wired orwireless links as shown schematically at L to achieve a selected brakingpressure. Braking pressure is typically defined in the art in terms ofvarious railcar weight classes.

The control circuit C is designed to control one or more components ofthe retarder system 20 to apply, maintain or change a predeterminedbraking pressure on the railcar wheel(s) as it travels and leaves thesystem 20 (as determined by the yard monitoring system M). Prior to thewheel(s) entering the system 20, the control circuit C can control theretarder system 20 to open and/or close the brakes 30 with minimalpressure. Once the railcar is in the system 20, the control circuit Ccan quickly change braking pressures applied to the wheel(s) inaccordance with the predetermined or active parameters set by the yardmonitoring system M and/or entered by an operator into the system 20 viaa conventional computer input device (not shown). Each of thesefunctions is accomplished by the programming of the control circuit Cand its communication with components in the system 20 which will beunderstood by one having ordinary skill in the art.

With further reference to FIGS. 7 and 8, the hydraulic circuit 32includes an electric motor 104 for powering a primary gear pump 106 anda secondary gear pump 108 which are interconnected so as to be operatedtogether, and are controlled for selective activation and deactivationby the control circuit C. The pumps 106, 108 are configured to variouslypump hydraulic fluid into the first manifold 32 a and the secondmanifold 32 b. The pumps 106, 108 are in communication with a supply ofhydraulic fluid contained in a cyclonic reservoir 110 having an upperportion 112 and a lower portion 114 such as is commercially availablefrom Eaton Corporation Hydraulics Operation of Eden Prairie, Minn. Suchcyclonic reservoir 110 is more fully disclosed in U.S. Pat. No.5,918,760, European Patent No. 0831238, Swedish Patent No. 510620 andGerman Patent No. 69705474.8, each of which is incorporated herein inentirety by reference. The upper portion 112 is provided with a switch116 for sensing and responding to a lower than desired hydraulic fluidlevel in the reservoir 110. When the motor 104 is energized, the primarypump 106 pumps hydraulic fluid, such as oil, from the reservoir 110 intothe hydraulic circuit 32 and, more specifically, to a high pressurefilter unit defined further by a high pressure filter 118, a cloggingswitch 120 and a check valve 122 as shown by the arrows A in FIG. 8.Hydraulic fluid normally flows through the filter 118 which acts toprotect contaminants from entering components in the hydraulic circuit32, and is directed towards a junction 124. In the event the filter 118becomes clogged or obstructed with contaminants carried by the hydraulicfluid, the clogging switch 120 will react to an increase in hydraulicfluid pressure differential and will transmit a signal to the PLC unitassociated with the control circuit C that the filter 118 needs to bechanged. At the same time, when the hydraulic fluid pressure exceeds apredetermined level (e.g. 50 psi) due to the clogging of the filter 118,the check valve 122 opens. This allows the hydraulic fluid to bypass thefilter 118 and continue into the hydraulic circuit 32 to the junction124 which is connected on one side to a pump unloader valve 126 and isconnected on an opposite side to a check valve 128. Hydraulic fluidcannot flow past the unloader valve 126 because it is closed, andtravels instead through the check valve 128 to a header 130 which isconnected to a pressure transducer 132 that is monitoring systempressure and controlling the motor 104. The hydraulic fluid is thendirected through a ball valve 134 to an accumulator 136, a manual flowcontrol valve 138 and a relief valve 140, as required by OSHA for amanual bleed-off and safety release of the accumulator's stored energy.As will be explained below, the pump 106 is periodically energized tocharge the accumulator 136 so that the accumulator 136 by itselfprovides pressurized hydraulic fluid which is used to provide poweredmovement of the brake 30 to the closed position and the Braking State.Periodically operating the pump 106 provides a savings cost to therailyard owner in contrast with prior art systems with constantlyrunning pumps which have been found to consume excessive electricalpower.

The accumulator 136 can include any one of a variety of hydraulic energystorage devices, such as compressed gas or a gas-charged accumulator orthe like. In the example shown, the accumulator 136 is constructed withtwo chambers that are separated, for example, by an elastic diaphragm orfloating piston. One chamber contains an inert gas under pressure or“pre-charge” that provides compressive force on the hydraulic fluid inthe hydraulic circuit 32. Here, the hydraulic circuit 32 is designed sothat the primary pump 106 pumps hydraulic fluid to the other chamber ofthe accumulator 136 for a predetermined time to charge or load theaccumulator 136 above its preloaded nitrogen charge (e.g. 2200 psi)until the hydraulic fluid reaches a predetermined maximum systempressure such as, for example, 3000 psi. In this charging phase,hydraulic fluid is prevented from flowing past the manual flow controlvalve 138 which is normally closed. The manual flow control valve 138can be opened to ensure that hydraulic fluid in the accumulator 136 isdirected back to the reservoir 110 at a regulated rate when the retardersystem 20 is shut down. The relief valve 140 is normally closed toprevent any fluid flow therethrough. However, if the pressure of thehydraulic fluid charged in the accumulator 136 exceeds the predeterminedmaximum system pressure by a certain amount, for example if the chargepressure reaches 3250 psi, the relief valve 140 is shifted open todischarge an appropriate amount of fluid back to the reservoir 110 untilthe maximum system pressure is satisfied at which time the relief valve140 is again closed.

As the primary pump 106 charges the accumulator 136 with hydraulicfluid, the system pressure, represented by arrows B in FIG. 9, begins tobuild up in the hydraulic circuit 32. This increasing system pressure istransmitted through the ball valve 134 and the header 130, the pressuretransducer 132 and to a pressure tap 142 to allow for manual systemmonitoring. System pressure is also transmitted to an accumulatorisolator 144 and a pilot controlled solenoid valve 146 for the operationof the isolator 144. Both the isolator 144 and the solenoid valve 146are used when it is desired to close the brakes 30 in the retardersystem 20, during the Braking State. Both the isolator 144 and thesolenoid valve 146 are normally closed so that there is no fluid flowtherethrough. System pressure is further transmitted to a pilotdirectional control solenoid valve 148 and a pilot controlled solenoidvalve 150, both of which are initially closed so that there is no fluidflow therethrough. In addition, system pressure is communicated via path152 so that it will push on a plunger of an unloader 154. This opens upa circuit which allows the system pressure to be transmitted to theunloader valve 126 where the high system pressure which has been builtup shifts the spool of the unloader valve 126 enabling all the hydraulicfluid to be unloaded such as represented at 156. Hydraulic fluid exitingthe unloader valve 126 is in communication with a flow diverter solenoidvalve 158, which is further in communication with a filter 160 of areturn filter unit to the reservoir 110. The return filter unit includesa clogging switch 162 and a check valve 164 which operates similarly toclogging switch 120 and check valve 122.

At this point, the accumulator 136 is fully charged, the motor 104 isturned off, the piston-cylinders 42 associated with the brakes 30 are ina retracted mode and the hydraulic circuit 32 is readied for a brakingevent in which each piston 62 may be extended as the accumulator 136 isdischarged. To close the brakes 30, the control circuit C sends a signalto energize and shift the pilot control solenoid valve 146 from theclosed condition to an open condition. As depicted in FIG. 10, hydraulicfluid, as represented by arrows C, then flows through the solenoid valve146 which acts as a pilot valve to a port of the accumulator isolator144. Here, the pressure of the hydraulic fluid acts on a spring biasedspool of the accumulator isolator 144 to effect opening thereof so thatfull pressure hydraulic fluid exits from the accumulator isolator 144and flows towards a pressure controlling arrangement where a particularhydraulic fluid operating pressure is selected. The pressure controllingarrangement is located in the first manifold 32 a and includes a pilotcontrolled proportional solenoid valve 166, and a main stage logicelement 168 connected to the solenoid valve 166 by a pilot line 170provided with a pair of orifices 172. The control circuit C sends anelectrical signal to energize the pilot control solenoid valve 166corresponding to a selected desired braking pressure. That is, thecontrol circuit C is configured to send a plurality of differentelectrical signals to the pilot control solenoid valve 166, each signalcausing the valve 166 to control the logic element 168 to achieve adifferent one of a plurality of different fluid pressures in the firstmanifold 32 a corresponding to a different one of a plurality ofdifferent braking pressures. The pilot controlled solenoid valve 166controls the logic element 168 by controlling the pressure of fluid inthe pilot line 170 coupled to the logic element 168. Pressure of fluidin the pilot line 170 is maintained proportional to the plurality of thedifferent signals. Pressure of fluid in the first manifold 32 a which iscontrolled by the logic element 168 is maintained proportional to thepressure of fluid in the pilot line 170. This arrangement is designed toprovide fine pressure control of the hydraulic fluid in the hydrauliccircuit, and provide a more efficient quick response to commands fromthe control circuit C.

Hydraulic fluid at the selected pressure is then monitored by a pressuretransducer 176 and delivered through multi-port connectors 178, 180 intothe cap-side chamber 66 of each piston-cylinder 42. Hydraulic fluidflowing towards a directional control valve 182 is prevented from flowtherethrough by sending a signal to energize solenoid valve 148 causingthe directional control valve 182 to close and prevent flow to thereservoir 110. Introduction of hydraulic fluid represented by arrows Cinto the cap-side chamber 66 forces each piston 62 into an extendedposition thus forcing the upper and lower levers 38, 40 to pivot aboutthe pin 36 and close the brake shoes 50 relative to one another. Thus,the brake 30 is actuated via a powered movement into a closed conditionand the Braking State with a selected braking pressure commensurate tothat set by the control circuit C. During brake closing, the solenoidvalves 150 and 158 are de-energized, while solenoid valves 146, 148 and166 are energized as noted above.

During movement of each piston 62 into its extended position, thehydraulic fluid will act to close a check valve 186 provided on thepiston 62 so that there is no fluid transfer through dampening orifices68 between the rod-side chamber 64 and the cap-side chamber 66.Hydraulic fluid flows out of the rod-side port 58 and, as represented byarrows C1, is discharged back into the hydraulic circuit 32 thusfacilitating movement of the brake 30 to the closed position.

When the brake 30 is in the closed position and with solenoid valves146, 148 and 166 energized, it is forced into an open position by arailcar wheel traveling into the brake 30 as illustrated in FIG. 11. Ashydraulic fluid represented by arrows D is forced from the cap-side port60 of each piston-cylinder 42, there is a rapid movement of piston rod62 and an increase or spike in the hydraulic fluid pressure. Suchpressure increase is transmitted to the logic element 168 in the firstmanifold 32 a which shifts to allow excess hydraulic fluid to bedirected to the reservoir 110 so that over-pressurization is avoided andthe selected system pressure is maintained. The excess hydraulic fluidflowing to the reservoir 110 passes through a back-pressure inducingcheck valve 188 so that a portion of the hydraulic fluid is transferredthrough multi-port connectors 208, 210, as represented by arrows D1, tothe rod port 58 of each piston-cylinder 42 to prevent cavitation duringrapid movement of each piston rod 62.

Referring to FIG. 12, when it is desired to move from the Braking Stateto the Relaxed State, the solenoid valves 146, 148 are de-energized andshifted closed by the control circuit C. Solenoid valves 150, 158 and166 are likewise de-energized by the control circuit C. In addition, thedirectional control valve 182 will assume a normally open position andallow hydraulic fluid as represented by arrows E to be sent therethroughpast check valve 188 and to a low pressure filter unit including returnfilter 160, a clogging switch 162 and a bypass-check valve 164 fordelivery to the reservoir 110.

It should be appreciated that at this point, no pressurized hydraulicfluid has been supplied to the rod ports 58 of the piston-cylinders 42.Instead, the hydraulic fluid is given a free path from the cap-sidechambers 66 back to reservoir 110 defining a relaxed position for thepiston-cylinder 42 in which the weight of the levers 38, 40 and thereturn springs 55, 57 will cause at least partial opening of the brakes30 via a non-powered movement. This feature provides for faster brakeopening reaction times and makes the retarder system 20 more energyefficient.

Referring to FIG. 13, when it is desired to provide a powered opening ofthe brakes 30, the secondary pump 108 pumps hydraulic fluid asrepresented by arrows F from the reservoir 110 through a filter 194 of ahigh pressure filter unit defined further by a clogging switch 196 and acheck valve 198 that operates similarly to clogging switch 120 and checkvalve 122. Hydraulic fluid is pumped by the secondary pump 108 past acheck valve 200 which is in communication with a relief valve 202similar to relief valve 140. That is, the relief valve 202 acts to allowhydraulic fluid flow back to the filter 194 when the pressure exceeds apredetermined maximum value (e.g. 600 psi). The hydraulic fluid leavingthe check valve 200 flows to a pilot controlled directional controlvalve 204 for assisting in a power open and flush and retraction of thepiston-cylinders 42. The directional control valve 204 is incommunication with a flow diverter solenoid valve 206 selectively usedto divert flow of heated hydraulic fluid to a cooler 190 in a coolingloop 192. The solenoid valves 146, 148 and 158 are de-energized andsolenoid valve 150 is energized to shift the spool of the pilotcontrolled directional control valve 204 so that hydraulic fluid pumpedby the secondary pump 108 flows through multi-point connectors 208, 210,as represented by arrows F, and to the rod-side chambers 64 to powerretract and flush the piston-cylinders 42. As hydraulic fluid enters therod-side chambers 64, the hydraulic fluid passes through the dampeningorifices 68 and pushes open the check valves 186 so that some hydraulicfluid flushes to the cap-side chambers 66. This flushing arrangementenables the hydraulic fluid fed into the cap-side chambers 66 to beslowly recycled into the hydraulic circuit 32 and through the filters118, 160, 194 so that the hydraulic fluid can be better cleaned. Thus,the piston-cylinders 42 assume retracted positions and the brakes 30 areactuated via a powered movement into the open position and a PowerOpen/Flush State using either the secondary pump 108 or both pumps 106,108 as described below. Hydraulic fluid flows out of the cap-sidechambers 66, as represented by arrows F1, and is discharged back to thehydraulic circuit 32.

As a feature of the disclosure, it may be possible to combine hydraulicfluid flows of the primary pump 106 and the secondary pump 108 to movethe brakes 30 to their powered open position with decreased cycle timesand faster speeds, if the accumulator 136 is at full hydraulic chargepressure. When primary pump 106 is available, both the solenoid valve150 and the flow diverter solenoid valve 158 are energized which resultsin the shifting of their spools and the combining of the hydraulic fluidflows from the primary pump 106 as represented by arrows G and thesecondary pump 108 as represented by arrows F. This combined pump flowis again delivered through the multi-port connectors 208, 210 into therod-side chambers 64 of the piston-cylinders 42 to effect a faster, moreefficient powered movement and opening of the brakes 30.

Referring to FIG. 14, should the hydraulic fluid become heated duringoperation, the solenoid valve 206 is energized to shift its spool sothat the heated hydraulic fluid, as represented by arrows H, passingthrough directional control valve 204 will flow to the cooler 190.Cooled fluid from cooler 190 is then returned back into the cyclonicreservoir 110.

A further feature of the disclosure resides in the provision of certaincomponents 144, 146, 148, 150, 154 (pilot port three), 182 which aredesigned to provide ultra low fluid leakage for maintaining accumulatorcharge. An anti-cavitation check valve 212 connects the low pressurereturn fluid directly to the rod-side 64 of each piston-cylinder 42. Inthe event the piston-cylinders 42 are forced open while the motor 104 isoff, the check valve 212 allows oil to freely flow from the low pressurereturn to the rod-side 64 of each piston-cylinder 42 to prevent cylindercavitation. All return hydraulic fluid is monitored by a temperaturesensor 214.

The reservoir 110 is a cyclonic reservoir defined generally by acircular tank that holds the returned hydraulic fluid. The fluid spinsand centrifugal forces push the entrained air to the center of thereservoir and the air bubbles will rise past an integrated baffle andnaturally aspirate in the upper portion 112 of the reservoir 110. Thecyclonic reservoir 110 provides for a more efficient reservoir used inthe processing of the returned hydraulic fluid in the hydraulic circuit32.

Referring to FIG. 15, should it be necessary to repair or replace theaccumulator 136, the motor 104 is turned off and the system must firstbe drained by manually opening the flow control valve 138 and thenmanually closing the ball valve 134. Following accumulatorrepair/replacement, the flow control valve 138 is manually closed andthe ball valve 134 is manually opened.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope of the inventionis defined by the claims, and may include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral languages of the claims.

What is claimed is:
 1. A system for retarding the speed of a railcar,the railcar comprising: a brake; a hydraulic actuator moving the brakebetween a closed position in which the brake applies braking pressure ona wheel of a railcar, and an open position in which the brake does notapply braking pressure on the wheel of the railcar; a hydraulic circuitconfigured with a first manifold and a second manifold, and providedwith a pump arrangement for supplying hydraulic fluid from a reservoirto the hydraulic actuator; and a control circuit coupled to thehydraulic circuit for controlling the flow of hydraulic fluid to movethe brake between the closed position and the open position, the pumparrangement being configured to supply the hydraulic fluid to one end ofthe hydraulic actuator and providing powered movement of the brake tothe closed position and to an opposite end of the hydraulic actuator andproviding powered movement of the brake to the open position; ahydraulic accumulator connected to the pump arrangement, wherein thepump arrangement is only periodically energized and charges thehydraulic accumulator, and wherein the hydraulic accumulator isconfigured to provide powered movement of the brake to the closedposition when the pump arrangement is de-energized; wherein the controlcircuit and the hydraulic circuit are configured to provide anon-powered movement of the brake from the closed position to the openposition without hydraulic fluid being forced from the hydraulicactuator and without hydraulic fluid being supplied to the hydraulicactuator such that the hydraulic fluid from the one end of the hydraulicactuator is given a free path therefrom back to the reservoir defining arelaxed position for the hydraulic actuator.
 2. The system of claim 1,wherein the closed position defines a Braking State, and the openposition defines one of a Relaxed State and a Power Open/Flush State. 3.The system of claim 2, wherein the pump arrangement is driven by amotor.
 4. The system of claim 3, wherein the pump arrangement comprisesa first pump used to provide powered movement of the brake to the PowerOpen/Flush State.
 5. The system of claim 3, wherein the pump arrangementcomprises first and second pumps used to provide powered movement of thebrake to the Power Open/Flush State.
 6. The system of claim 2, whereinthe hydraulic actuator comprises a piston movably disposed in acylinder, wherein pressurized hydraulic fluid enables the piston toextend from the cylinder into an extended position to move the brakeinto the Braking State, and wherein pressurized hydraulic fluid enablesthe piston to retract into the cylinder in a retracted position to movethe brake into the Power Open/Flush State.
 7. The system of claim 6,wherein the piston defines an orifice therethrough in communication witha check valve and wherein the orifice and the check valve facilitateflushing of hydraulic fluid from a rod-side of the cylinder to acap-side of the cylinder when the piston is moved from the extendedposition to the retracted position in the Power Open/Flush State.
 8. Thesystem of claim 6, wherein the control circuit and the hydraulic circuitare operated to provide non-powered movement to the Relaxed Statewithout supplying pressurized hydraulic fluid to the cylinder.
 9. Thesystem of claim 2, wherein the brake includes a set of levers and returnsprings, and wherein, in the Relaxed State, the hydraulic fluid flowsfreely from a cap-side chamber of the hydraulic actuator to thereservoir such that weight of the levers and return force of the springscauses at least partial opening of the brake.
 10. A system for retardingthe speed of a railcar, the railcar comprising: a brake; a hydraulicactuator moving the brake between a closed position in which the brakeapplies braking pressure on a wheel of a railcar, and an open positionin which the brake does not apply braking pressure on the wheel of therailcar; a hydraulic circuit configured with a first manifold and asecond manifold, and provided with a pump arrangement for supplyinghydraulic fluid from a reservoir to the hydraulic actuator; a controlcircuit coupled to the hydraulic circuit for controlling the flow ofhydraulic fluid to move the brake between the closed position and theopen position, the pump arrangement being configured to supply thehydraulic fluid to one end of the hydraulic actuator and providingpowered movement of the brake to the closed position and to an oppositeend of the hydraulic actuator and providing powered movement of thebrake to the open position; and a hydraulic accumulator connected to thepump arrangement; wherein the control circuit and the hydraulic circuitare configured to provide a non-powered movement of the brake from theclosed position to the open position without hydraulic fluid beingforced from the hydraulic actuator and without hydraulic fluid beingsupplied to the hydraulic actuator such that the hydraulic fluid fromthe one end of the hydraulic actuator is given a free path therefromback to the reservoir defining a relaxed position for the hydraulicactuator; wherein the closed position defines a Braking State, and theopen position defines one of a Relaxed State and a Power Open/FlushState; wherein the pump arrangement is driven by a motor; wherein thepump arrangement is periodically energized to charge the hydraulicaccumulator so that, upon de-energization of the pump arrangement, thehydraulic accumulator provides pressurized hydraulic fluid which is usedto provide powered movement of the brake to the Braking State; andwherein the hydraulic circuit comprises a cyclonic reservoir for holdinga supply of hydraulic fluid, the cyclonic reservoir being incommunication with the pump arrangement and configured for processinghydraulic fluid returned with entrained air in the hydraulic circuit.11. The system of claim 10, wherein the pump arrangement is connected toa first filter, a first clogging switch and a first filter check valve.12. The system of claim 11, wherein the pump arrangement is connected toa second filter, a second clogging switch and a second filter checkvalve.
 13. The system of claim 11, wherein the first filter is connectedto a first check valve and an unloader valve.
 14. The system of claim13, wherein hydraulic fluid flows through the first filter and the firstcheck valve, and a ball valve for delivery to the hydraulic accumulatorwhich is charged to a predetermined system pressure.
 15. The system ofclaim 14, wherein the system pressure is transmitted to an accumulatorisolator and a first pilot controlled solenoid valve connected to theaccumulator isolator.
 16. The system of claim 15, wherein the systempressure is further transmitted to a directional control solenoid valveand a second pilot controlled solenoid valve.
 17. The system of claim16, wherein system pressure is further transmitted to an unloader whichenables the system pressure to operate the unloader valve such that asupply of pressurized hydraulic fluid is available at an outlet thereof.18. The system of claim 17, wherein the unloader valve is incommunication with a first flow diverter solenoid valve that is furtherin communication with a return filter connected to the cyclonicreservoir.
 19. The system of claim 18, wherein the control circuit sendsa signal to operate the first pilot controlled solenoid valve to enableflow of pressurized hydraulic fluid through the accumulator isolator toa pressure controlling arrangement which is located in the firstmanifold and is configured to respond to different signals sent from thecontrol circuit to maintain a desired selected system pressurecorresponding to a desired braking pressure for holding the brake in theclosed position.
 20. The system of claim 19, wherein the pressurecontrolling arrangement includes a pilot controlled proportionalsolenoid valve, a logic element and a pilot line connecting the pilotcontrolled proportional solenoid valve with the logic element.
 21. Thesystem of claim 20, wherein pressurized hydraulic fluid at the selectedsystem pressure maintained by the pressure controlling arrangement isdelivered to the hydraulic actuator to provide the powered movement ofthe brake to the closed position.
 22. The system of claim 21, whereinduring the powered movement of the brake to the closed position, thefirst pilot controlled solenoid valve, the directional control solenoidvalve, and the pilot controlled proportional solenoid valve areenergized.
 23. The system of claim 22, wherein the first pilotcontrolled solenoid valve, the directional control solenoid valve, thesecond pilot controlled solenoid valve, the first flow diverter solenoidvalve, and the pilot controlled proportional solenoid valve arede-energized when the brake is moved to the Relaxed State.
 24. Thesystem of claim 23, wherein the pump arrangement and the second filterare in communication with a second check valve, a pilot controlleddirectional control valve and a second flow diverter solenoid valve. 25.The system of claim 24, wherein the second flow diverter solenoid valveis in communication with a cooler connected to the cyclonic reservoir.26. The system of claim 25, wherein the second pilot controlled solenoidvalve is energized to control the pilot controlled directional controlvalve such that pressurized hydraulic fluid is delivered to thehydraulic actuator to provide a powered movement of the brake to theopen position.
 27. The system of claim 26, wherein, should thepressurized hydraulic fluid become heated, the second flow divertersolenoid valve is energized to divert flow from the pilot controlleddirectional control valve to the cooler.
 28. The system of claim 27,wherein, if the hydraulic accumulator is fully charged, the second pilotcontrolled solenoid valve and the first flow diverter solenoid valve areenergized to permit combined hydraulic fluid flow via the pumparrangement to provide the powered movement of the brake to the openposition.
 29. A system for retarding the speed of a railcar, the railcarcomprising: a brake; a hydraulic actuator moving the brake between aclosed position in which the brake applies braking pressure on a wheelof a railcar, and an open position in which the brake does not applybraking pressure on the wheel of the railcar; a hydraulic circuitconfigured with a first manifold and a second manifold, and providedwith a pump arrangement for supplying hydraulic fluid from a reservoirto the hydraulic actuator; and a control circuit coupled to thehydraulic circuit for controlling the flow of hydraulic fluid to movethe brake between the closed position and the open position, the pumparrangement being configured to supply the hydraulic fluid to one end ofthe hydraulic actuator and providing powered movement of the brake tothe closed position and to an opposite end of the hydraulic actuator andproviding powered movement of the brake to the open position; a pressurecontrolling arrangement which is located in the first manifold and isconfigured to respond to different signals sent from the control circuitto maintain a desired selected system pressure corresponding to adesired braking pressure for holding the brake in the closed position;and an anti-cavitation check valve connected to hydraulic actuator,wherein the hydraulic actuator comprises a piston movably disposed in acylinder, and wherein the anti-cavitation check valve directs a portionof the hydraulic fluid directed to the reservoir to a rod-side of thecylinder to prevent cavitation during a rapid movement of the pistonwithin the cylinder; wherein the control circuit and the hydrauliccircuit are configured to provide a non-powered movement of the brakefrom the closed position to the open position without hydraulic fluidbeing forced from the hydraulic actuator and without hydraulic fluidbeing supplied to the hydraulic actuator such that the hydraulic fluidfrom the one end of the hydraulic actuator is given a free paththerefrom back to the reservoir defining a relaxed position for thehydraulic actuator.